Body is the readable text of the turn, taken from the stored event's text. Empty when the event carried a payload of some other shape — this route reads transcripts and does not invent prose for turns that are not one.
Commit is the full sha this turn produced, empty when the turn changed nothing. It is ECHOED from the transcript, and the authority is the commit itself: it carries the Hanzo-Session:/Hanzo-Turn: trailer, or a note under refs/notes/hanzo-provenance saying the same, so the claim is checkable at source with the command in verify.
Seq is this turn's POSITION in the session's log — monotonic from 1, per session — and it is what a commit's Hanzo-Turn: trailer names. It is not a count of anything: the count is turns on the summary beside it.